The invention belongs to the field of preparation for medicaments, and in particular relates to a process for producing heparin sodium. In the process, the skin of small intestines of a pig from which mucosae is removed serves as a raw material, and the heparin sodium product is obtained by preprocessing, adsorbing, washing, eluting, precipitating and drying sequentially, wherein in the preprocessing step, the skin of the small intestines is crushed into paste, and then salt special for sausage casing is added into the paste for pickling; and in the adsorbing step, acrylic acid strongly basicanion exchange resin, namely rohm and haas FPA98 resin is adopted. The production process can effectively solve the problems of environmental pollution and the like caused by a large amount of waste intestine residue of the pig (the skin of the small intestines primarily), further increases the added value of the small intestines of the pig, and reduces the production cost; and the purity of the product is over 120 titers/mg.